1. Field Of The Invention
This invention relates to the field of standard electronic modules and, more particularly, to the field of standard electronic modules having RF/microwave packaging therein.
2. Description Of Related Art
The performance and reliability of RF systems, and the ability to accurately predict the reliability of such systems, can be affected by interconnections, substrate mounts, thermal management, and the variety of materials used in the circuits. All of these design parameters can be positively impacted by effective subsystem packaging. The use of circuit size reduction technology provides an efficient implementation of standardized form-fit standard electronic module (SEM) RF modules. However, the use of smaller circuit sizes in an RF module accentuates the reliability of the interconnections, substrate mounts, thermal management, and the variety of materials used in the circuits. Interconnections and connectors provided in the RF module must be made in a smaller volume; substrate mounts in the RF module must support a variety of materials such as silicon, gallium arsenide, ceramics and glass; and thermal management must account for denser heat fluxes and thermal expansion related stresses resulting from the heat generated in the RF module and the different material provided therein.
The performance integrity of the interconnections in the RF module is of particular concern. The physical location, size, position relative to the electrical ground, stability of the ground, and the dielectric properties of the material around the RF signal carrier all affect RF transmission line performance. These factors are extremely critical and vary most at interconnection points. Consequently, the design and integrity of these interconnects is critical to RF performance and reliability. This is particularly true with a dense packaging of monolithic microwave integrated circuit (MMIC) devices where the area available for interconnects is minimal. These interfaces must be carefully controlled in a manner that is standardized so that design and manufacturing costs are minimized.
The substrate and mounting technique used for advanced circuitry is also critical to reliable performance. Ideally, the substrate and mounting techniques do not alter the electrical characteristic of the interconnect. Moreover, the substrate and mounting techniques should not interfere with efficient heat removal from the device, or have a negative impact on the coefficient of thermal expansion induced stress.